Process for removing sulphur dioxide and compounds from food products



Patented Apr. '5, 1927.

UNITED STATES PATENT OFFICE.

IUDWIG ROSENSTEIN, OF- SAN FRANCISCO, CALIFORNIA.

PROCESS FOR REMOVING SULPHUR DIOXIDE AN D COMPOUNDS FROM FOOD PiRODUCTS.

Ho Drawing.

This invention'relates to a process for the removal of sulphur dioxide or compounds thereof from stage of their ried fruits and other food products which have been treated at some preparation for the market with sulphur dioxide.

As is well known, the appearance and keeping quality of dried fruits are greatly improved by treatment with sulphur dioxide (usuall called sulphuring or bleaching), prior to t air being dried. However, excessive quantities of sulphur dioxide or compounds must not be allowed to remain in the finished products, as "these are considered harmful, and are in fact, strictly limited by certain governments.

I have found that sulphur dioxide thus ordinarily retained in the fruit may be effectively removed to any desired extent from the sulphured product by utilizing the reaction which sulphur dioxide or sulphites undergo when brought incontact with a peroxide such as hydrogen peroxide. By this reaction the sulphur dioxide or sulphite is oxidized to sulphate which latter is entirely harmless in food products and against which there is no legislation either in this country or abroad so far as is known to appvlipant.

. en sodium peroxide is used oxide compound, the reaction is:

" SO,+Na O =Na SO Or, if hydrogen peroxide is used, the reaction is:

as the per- While this latter reaction indicates the formation of sulphuric acid which might be considered as a harmful ingredient, this compound need not actually be formed. The addition of a mild alkali such as sodium bicarbonate during the treatment prevents it, though in many cases, suflicient salts of weak acids are normally present in the fruit to react with the small amount of sulphuric acid first formed and thereby render it harmless.

The following description indicates one method of carryin out my. invention: A certain sample of ried apricots showed on anal sis the presence of 400 milli ams of sulphur dioxide per kilo m. Pre iminary tests also showed that the fruit would retain on its surface approximately 18% of its k weight of water when dipped therein and .be such as to w Application illedllar'ch 1a, 1926. Serial No. 95,799.

rapidly removed; in other words one kilogram would retain 180 grams of water. 3

the above described dipping method. The

peroxide solution may be applied by spraying, dripping, or any other means; nor need the quantity of eroxide applied to the fruit the sulphur dioxide contained therein, but may be either more or less than this amount;

other alkali necessary in all cases:

-Peroxides other than hydrogewperoxide, but having a similar action with sulphur dioxide or sulphites may be used, and of course any soluble salts formed may be washed away with water if desired.

I claim:

1. The process for removin undesirable sulphur com ounds from dried fruit which comprises su jectin the fruit to the action of hydrogen peroxide;

2. The process for removin undesirable sulphur com ounds from dried fruit which comprises su jecting the fruit to the action of hydrogen peroxide in aqueous solution.

3. The process for removing undesirable sulphur compounds from dried fruit which comprises su jecting the fruit to the action o by ogen peroxide .in aqueous solution by d1 ing the fruit therein.

4. The process for removing undesirable sulphur com ounds from dried fruit which comprises su jectin the fruit to the action 76 e chemically equivalent to nor is the addition of sodium bicarbonate or the fruit of the liquid adhering thereto, the

active chemical in the amount of liquid ad hering to the fruit being so proportioned as to react with the quantity of sulphur compound it is desired to remove from the fruit.

6. The process for removin undesirable sulphur compounds from dried fruit which comprises applying to the surface of the fruit an aqueous solution of a peroxide and an alkali. I

7:. The process for removing undesirable sulphur compounds from dried fruit which comprises applying to the surface of the reaaoao 

